The present invention relates to a plumbing fitting and particularly one for use with a fire suppressing sprinkler system and its method of manufacture.
Installation of sprinkler heads which utilize metal threads to a typical water system employed in fire suppressing systems typically involves threading the tapered metal threaded sprinkler head into a threaded polymeric socket, in turn, bonded to a polymeric water supply line using a bonding adhesive. If over tightening of the metal sprinkler head occurs, it can result in fractured polymeric sockets for receiving the fire sprinkler head or, if under tightened, water leaks can result. These problems exist, in part, because it is desirable to have the sprinkler heads specifically aligned to present a desired sprinkling pattern or, in some installations, an aesthetically pleasing common appearance. In order to do so, typically a sprinkler head wrench is employed to prevent damage to the sprinkler head during installation and approximately 25 to 50 foot-pounds of torque is applied to install the sprinkler head. Alignment of the sprinkler heads then frequently requires additional tightening as much as a quarter turn to properly align the sprinkler heads. In horizontally extending sprinklers, it is necessary for the sprinkler head deflector to be substantially horizontal and the sprinkler head fitting square to the receiving socket. Typical seals, such as O-ring type seals, have been problematical in such installations in which under tightening can cause leaks, while overtightening in an effort to obtain a seal can result in stripping or fracturing of the receiving polymeric threads of the water supply socket.
There remains a need for an improved plumbing fitting for receiving a sprinkler head which includes a seal shape that allows a sprinkler head to be mounted to a receiving socket of a fire suppression water supply line using a lower torque to achieve a seal, thereby preventing damage to the sprinkler head while providing a watertight seal and proper alignment of the sprinkler head with respect to other sprinkler heads and/or to the water supply line.